Help Please Identify Root Rot

I currently grow a 60 Day Wonder Auto in the Aero Plantit DWC system with a reservoir of about 12.5 lt. I am into the third week of growing phase. The light I use is the 144 Marshydro Reflector, the temperature ranges from 23 to 26 max celcius, and the humidity never goes below 55% with top 60 - 63%, the ph due to the DWC, fluctuates from 6.0 when i correct it to 7.2 max, the res temp usually ranges from 18 C to 20 C.
Although haven't smelled something funny in the res other than the nutes, I just lost one baby to root rot and I am concerned, I am bit worried about how the roots look.
I use Adv. Nutrients Sensi grow, light feed, about 1 ml / lt for basis, Sensi Cal Mag, Voodoo, Tarantula, Sensizym, Piranha at the same ratio, and B 52 half. Here are some photos of yesterday and this morning any help will be appreciated.

Touch those roots lightly and see if they have any slime on them. If slimy, start treating. They usually go a little slimy before the brown comes in with root rot.

Hi there cant say thay feel slimy just stranded and I saw tonite that the first 4 leaves have brown spots

voodoo juice Decompose organic matter to create extra nutrition for your plants
organic is a no no in Dwc